First, no matter how many ideas you can come up with, what matters is execution. Ideas are cheap a dozen. I would agree that mapping out an evolution for a product or service, or pivoting to something different, is important. Specially when you are just getting started and you don’t know if your idea will flop. So better be ready to pivot ASAP.
Now, that said, I would like to offer a complementary idea to speed up the process of creating more ideas as suggested on Idea #1. You don’t need to come up with 100 ideas right off the bat.
Instead focus on your first 10 ideas, then list them on an 10x10 matrix or spreadsheet and contrast one on one (see picture below) to generate subsets of the original 10 ideas. Yes there is a repetitive pattern here, for example Idea 1.2 versus Idea 2.1. But if you see it from how one idea influences the other you can surely give it a different spin or tweak. When comparing ideas to generate subsets, think of what could go with that idea before, during and after a buyer or end user purchases it (paraphrasing Jay Abraham). Think of new features or value proposition for each iteration. You should come up with 90 fresh new ideas. And that’s how you get your 100 ideas in no time.